We could muse for a long time on the deficiencies of social categorisation measures, but that would take us a long way from Brexit, so I will resist.

The effect of the fragmentation of the pro-remain vote into separate camps (ChangeUK, LibDem, Green etc) is difficult to assess. Because the EU voting uses a version of proportional representation it does not matter too much in one sense because the 'pro-remain/pro-leave' representation more or less follows the sum of the votes for that viewpoint, rather than the separate parties. However there is a complication of a minimum threshold of I think 10% (or more in some places), and that could end up eliminating a viewpoint entirely if it becomes too fragmented.